1. Field of the Invention
The present invention relates to a semiconductor device formed by mounting a semiconductor chip on a lead frame and a method for manufacturing the same and, more particularly, to a TCP (tape carrier package) type semiconductor device which is improved in mounting on a printed circuit board by reflow soldering.
2. Description of the Related Art
Conventionally, as shown in FIG. 1, a TCP type semiconductor device is sealed by applying liquid resin 3 to a region containing leads (inner lead sections) 2 above a semiconductor chip 1 after ILB (inner lead bonding) is executed and then curing the resin 3 by heat treatment. This method enables the semiconductor device to be thinned greatly.
A carrier tape used in the TCP type semiconductor device is called a TAB (tape automated bonding) tape (TAB type lead frame). The carrier tape is constituted as follows. Copper foil is laminated on an insulating film of polyimide or the like and then photoetched to form leads each having an inner lead section and an outer lead section (wiring pattern). The carrier tape having such a constitution is generally flexible and suitable for mounting a semiconductor device on a printed circuit board.
Since, however, the carrier tape is easy to be bent or distorted, its flatness is difficult to maintain. If the bend or distortion of the carrier tape adversely affects the flatness of the outer lead sections, no semiconductor device can be mounted stably. If the flatness of the outer lead sections is lost, it becomes more difficult to mount the semiconductor device on a printed circuit board by reflow soldering, resulting in failure in mounting.
To cope with the above problem, for example, Jpn. Pat. Appln. KOKAI Publication No. 3-125440 discloses securing the flatness of a carrier tape by providing the carrier tape with a reinforcing plate. However, in the ILB of the TCP type semiconductor device described above, connecting electrodes 4 such as gold bumps are formed on the electrode pads of the semiconductor chip 1, and the inner lead sections of the leads 2 of the carrier tape are bonded to the connecting electrodes 4 by thermocompression bonding. For this reason, they can be bonded in a relatively stable state when the number of leads 2 is large, but they cannot be bonded stably when the number is small. If the bonding is unstable, the connecting electrodes 4 come off, or the flatness of the carrier tape cannot be maintained.